This is us: Mareike Grotheer

Mareike Grotheer has been leading the Lise Meitner Research Group NeuroLearn since May. A conversation about her research on neuroplasticity, innovative research methods, her fascination with early developmental phases in babies, and what motivated her to come to the Institute.

Mareike, you have been at the Institute since May. To start, we would like to learn more about your scientific background. What led you to your research topic and which stages shaped your path there? 

Mareike Grotheer: I did my PhD in Jena. At that time, I worked on so-called repetition suppression effects, that is, the question of how what we are currently seeing influences what we expect next. 

Already during that time, I was very interested in specialized regions in the visual system. There are areas in the brain that respond selectively to certain categories, for example to faces. These regions are essential. If such an area fails, the corresponding stimulus can no longer be processed properly. I found that fascinating and wondered whether something like this also exists for numbers. This question then stayed with me beyond my PhD and was the starting point for my first independent research program. 

With a DFG fellowship, I then went to Stanford University and worked there on understanding the neural underpinnings of numbers and words. After my time in Stanford, I set up my own junior research group at the University of Marburg. There, I initially mainly worked on learning in the context of education, for example on reading and arithmetic. At the same time, my interest in early development grew stronger and stronger. Working with infants, which I had already encountered in Stanford, had a particularly strong appeal to me.

What makes this early phase, research with babies, so interesting for you? 

Mareike Grotheer: Because the brain is most malleable in this phase. Babies learn an enormous amount in a very short time, and the brain changes very quickly in the process. I am interested in whether learning works differently in this phase. Do babies learn faster because their brains can still be profoundly restructured? While much is already stable in adults, everything in babies is still under construction. 

To understand this, it is not enough to take snapshots. We have to follow development directly. That is why we work longitudinally and accompany babies over time. 

One example is learning to crawl. We want to combine two approaches: large datasets in which we compare many babies at different developmental stages, and our own studies in which we examine individual babies multiple times while they develop this skill. 

This allows us to ask very innovative questions. Does the brain change continuously or rather in steps? Does structural change come first, or behavior? Such dynamics become visible only when development is followed longitudinally.

You are expanding your original focus on reading and arithmetic. What has changed? 

Mareike Grotheer: The focus has become significantly broader. While I used to focus strongly on reading and arithmetic, today I am concerned with general principles of learning. 

This means that we no longer only ask what happens in the brain when we learn to read or do arithmetic, but more generally what happens when we learn something new. 

One example is a planned experiment in which children, adults, and older adults will learn to juggle. We plan to examine how the brain changes in different age groups and whether age plays a role in how learning is anchored in the brain.

A central component of your research is the investigation of myelin. What role does this structure play? 

Mareike Grotheer: Myelin is a kind of insulation of nerve pathways. You can imagine it like a cable. The better it is insulated, the more efficiently the signal is transmitted. This is important for the brain because signals must arrive not only quickly but also as synchronously as possible. If myelination is disrupted, this can have considerable negative effects and alterations in myelin have even been linked to developmental and neurological disorders. 

For a long time, myelin was rather neglected because it was assumed that it is established at birth and then no longer changes. In recent years, however, especially in animal studies, it has been shown that myelination is closely linked to learning. We want to better understand this relationship in humans.

What methods do you use to investigate myelin? 

Mareike Grotheer: We work with quantitative magnetic resonance imaging, a comparatively new method. It allows us to measure myelin content in the brain directly and very precisely at the level of individual image points. 

This is a major advance compared to earlier methods, which could only capture general changes in white matter without knowing exactly what had changed. 

Another advantage is that the data can even be compared between different scanners. This opens up new possibilities for multi-site research. The disadvantage is that the measurements take somewhat longer, which can be a challenge especially in studies with children and babies.

In a recent study, you and international colleagues investigated how gray and white matter develop in infancy. What did you find? 

Mareike Grotheer: We were able to show that gray and white matter develop synchronously in infancy. Until now, these two components of the brain have mostly been considered separately. However, our results demonstrate that their development is closely coordinated, and that it is therefore important to consider both structures simultaneously. 

Gray matter is mainly responsible for the processing of information, while white matter provides the connections between different brain regions. In our data, we see that myelination proceeds synchronously in both structures. When myelin is built up in white matter pathways, this also happens in their corresponding processing areas of the cortex. 

It is particularly interesting that this synchrony is not equally pronounced in all children. We observe clear differences between preterm and full-term babies. In preterm infants, this synchrony is weaker. 

In addition, there are first indications that this early synchrony could play a role for later development. Children in whom gray and white matter are particularly well synchronized tend to show better motor abilities in toddlerhood. 

This suggests that the organization of the brain already sets important directions for further development at a very early stage.

What do your research plans for the coming years look like? 

Mareike Grotheer: In the short term, we focus on longitudinal studies in clearly defined developmental phases, especially in the first year of life and around school entry. 

School entry is particularly interesting to me because the conditions of learning change fundamentally at this time. Children move from rather incidental learning to a situation in which they are expected to learn in a targeted and systematic way. We are interested in how this transition is reflected in the brain. 

In the long term, we want to follow developmental trajectories over very long periods, ideally from the womb into adulthood. 

This is methodologically challenging, especially because the movement of fetuses make imaging them more difficult. At the same time, this is precisely where there is a great opportunity. Only if we accompany the same individuals over a long period can we understand how early development, already before birth, is related to later milestones such as school entry.

What role do collaborations play? 

Mareike Grotheer: Collaborations are central. Within the Institute, I see clear connections to research that focuses on the influence of environmental factors on brain development and on development across the lifespan. 

Beyond the Institute, I continue to work closely with colleagues from my time at Stanford who shape the field of developmental cognitive neuroscience. In addition, there is a close collaboration with the University of Washington, where innovative computational data analysis methods are being developed. This combination of a developmental perspective and cutting-edge analysis methods has proven to be very productive.

Exchange with the public is also important to you. You established a special format in Marburg. Can you describe it? 

Mareike Grotheer: In Marburg, we regularly visited PEKiP groups, that is, groups of parents with their babies, and talked about our research with these groups. 

What was special about these visits was that these were not traditional talks. I sat with a small group of parents while their babies crawled around and had conversations with them. For me, this was a particularly nice form of exchange because it was very direct and interactive. The parents asked many questions, shared their own experiences, and a real dialogue about brain development emerged.

Do you plan to continue this format in Berlin? 

Mareike Grotheer: Yes, I would very much like to do that. I will start by looking for suitable partners in Berlin, for example institutions or programs that already offer such crawling groups. 

The idea would then be to go there free of charge, present our research, and seek exchange.The exchanges we had in Marburg were very positive, and colleagues, for example at the University of Washington, have adopted similar formats, also with good feedback. That is why I am optimistic that this can also be established well in Berlin.

Finally, what motivated you to move to the institute? 

Mareike Grotheer: Above all, the thematic fit. I fam convinced that this is the perfect place for my research. It connects well to existing topics and complements them in a meaningful way. 

In addition, I was impressed by the dynamic development of the institute. It became clear to me that the institute will continue to play a major role in shaping our understanding of human brain development, and I wanted to contribute to that. 

 

About Mareike

Mareike Grotheer completed her PhD in psychology at Friedrich Schiller University Jena and received a DFG fellowship for Stanford University, where she conducted research for five years in the Vision and Perception Neuroscience Lab. In 2021, she moved to Philipps University Marburg as a junior group leader and from 2025 as a professor. Since May 2026, she has led her own research group at the Max Planck Institute for Human Development. 

More about the Lise-Meitner Group NeuroLearn:
LMG Neuroplasticity in Development and Learning | Max Planck Institute for Human Development 

 

Original publication 

Zika, S., Chang, K., Orhon, A., Kruper, J., Tyagi, C., Yan, X., Tung, S., Grill-Spector, K., Rokem, A., & Grotheer, M. (2026). Cortical and white matter myelination proceed in concert during early infancy. Nature Communications, 17, Article 5353. https://doi.org/10.1038/s41467-026-73366-9